This invention relates to pallet handling equipment, and more particularly to a puller for connecting a drag line to a loaded pallet for relocating the pallet.
Devices for connecting a drag line to a loaded pallet are known in the prior art. For example, U.S. Pat. No. 3,807,786 to Alegria describes a scissors-type clamp having toothed jaws for engaging opposite sides of a central joist of the pallet. Clamping force is generated by tension in a draw chain connecting the clamp to a vehicle for moving the pallet.
A disadvantage of the Alegria clamp is that the jaws can slip out of engagement with the joist. The joist is typically a wood member with the wood grain running lengthwise. The teeth of the jaws, being oriented across the grain, do not penetrate sufficiently deep into the joist for moving a heavily loaded pallet. Thus the jaws tend to slip along the grain of the joist instead of biting into the wood.
Another disadvantage of the Alegria clamp is that the jaw mechanism comprises a number of moving parts. Consequently, it is expensive to make, subject to wear, and dangerous to use.
Other prior art pallet-connecting devices hook behind a transverse board of the pallet. See, for example, U.S. Pat. No. 4,094,544 to Spaine, and U.S. Pat. No. 4,421,353 to Smith, Jr. These devices require access behind a transverse board of the pallet for engaging the hook. These hook-type devices are difficult or impossible to use unless the pallet has transverse boards that are separated sufficiently to clear the hook (open construction). Thus pallets that have solid panel (closed) construction for carrying fragile loads such as sacks of cement cannot be engaged by the hook. Moreover, when there are separated, transverse boards above, but not below the joist, these devices are difficult to keep hooked until tension can be applied to the drag line.
Thus there is a need for a pallet puller that is reliable, safe, inexpensive, and easy to use on a pallet of open or closed construction, whether or not the pallet has transverse boards below the joist.